The Science Behind TED's 18-Minute Rule

Ideas are the currency of the 21st century. You can have brilliant ideas—truly revolutionary ideas—but if you cannot persuade others to act, those ideas don’t matter. Today, thanks to the world-famous TED conference, independently organized TEDx events, and new research into the science of persuasion, we've learned more about what moves people than we've ever known. Given the fact that TED talks are streamed more than 2 million times per day, I would argue that, like it or not, your next presentation is being compared to TED. TED talks are inspiring, educational, informative, and wildly addictive. The length of a TED talk—18 minutes—is one of the key reasons behind the format’s success.

It doesn't take a scientist to know that you cannot inspire people if you put them to sleep. But scientists are beginning to identify how long most people can pay attention before they tune out. The range seems to be in the area of 10 to 18 minutes. TED organizers reached the conclusion that 18 minutes works best. Nobody, no matter how famous, wealthy, or influential is allowed to speak more than 18 minutes on a TED stage—it doesn't matter if your name is Bill Gates, Sheryl Sandberg, Bono, or Tony Robbins, who joked that he found the 18-minute rule extra challenging because his shortest seminar was 50 hours!

TED curator Chris Anderson explained the organization’s thinking this way:

It [18 minutes] is long enough to be serious and short enough to hold people’s attention. It turns out that this length also works incredibly well online. It’s the length of a coffee break. So, you watch a great talk, and forward the link to two or three people. It can go viral, very easily. The 18-minute length also works much like the way Twitter forces people to be disciplined in what they write. By forcing speakers who are used to going on for 45 minutes to bring it down to 18, you get them to really think about what they want to say. What is the key point they want to communicate? It has a clarifying effect. It brings discipline.

The 18-minute rule also works because the brain is an energy hog. The average adult human brain only weighs about three pounds, but it consumes an inordinate amount of glucose, oxygen, and blood flow. As the brain takes in new information and is forced to process it, millions of neurons are firing at once, burning energy and leading to fatigue and exhaustion. Researchers at Texas Christian University are finding that the act of listening can be as equally draining as thinking hard about a subject. Dr. Paul King calls it “cognitive backlog.” Like weights, he says, the more information we are asked to take in, the heavier and heavier it gets. Eventually, we drop it all, failing to remember anything we've been told. In King’s own research, he found that graduate students recall more of the information they learn when they go to class three days a week for 50 minutes instead of one day a week for three hours. Although most students say they’d prefer to get the class over with at once, they retain more information when receiving the information in shorter amounts of time.

I can already hear the pushback—How can I possibly be expected to say everything I need to say in 18 minutes? A lot can happen in 18 minutes. John Kennedy inspired a nation to look to the stars in 15 minutes. In a 15-minute TED talk, Facebook COO Sheryl Sandberg inspired millions of women to “lean in.” Steve Jobs gave one of the most popular commencement addresses of our time at Stanford University and he did it in 15 minutes. It took Dr. Martin Luther King a bit longer to share his dream of racial equality—he did it in 17 minutes. If these leaders can inspire their audiences in 18 minutes or less, it’s plenty of time for you to pitch your idea!

(Photo: Bono speaking at TED 2013, photo by: James Duncan Davidson)

Communication Coach, Author, Talk Like TED: The 9 Public Speaking Secrets of the World’s Top Minds (March 2014, St. Martin’s Press)

Bill Sheaffer PMP

Senior IT Project Manager at Phoenix Contact

8mo

Great idea and inspiration to save time. Get to the key points!

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Houtan Emad

Product Marketing Manager

1y

Great read! Keen to apply this to more technical presentations and demos 🔩

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Chris Sheen

Director of Social @ Celonis

3y

An oldie, but a goodie - Great advice. "If these leaders can inspire their audiences in 18 minutes or less, it’s plenty of time for you to pitch your idea!"

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Josiah Johnston

Addressing societal problems through advanced computations and collaborations

3y

It would be great if you can give some scientific sources for "10 to 18 minutes". Your single paraphrased source says "50 minute sessions are better than 3 hour sessions". This paper says there's a pervasive myth of 10-15 minute attention span that is not backed by any serious research: https://journals.physiology.org/doi/pdf/10.1152/advan.00109.2016

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